Physiological and biochemical responses of three Veneridae clams exposed to salinity changes

Given their global importance, coastal marine environments are a major focus of concern regarding the potential impacts of climate change, namely due to alterations in seawater salinity. It is known that environmental characteristics, such as salinity, affect immune and physiological parameters of bivalves. Nevertheless, scarce information is available concerning the biochemical alterations associated with salinity changes. For this reason, the present work aimed to evaluate the biochemical responses of three venerid clam species (Venerupis decussata, Venerupis corrugata, Venerupis philippinarum) submitted to salinity changes. The effects on the native (V. decussata and V. corrugata) and invasive (V. philippinarum) species collected from the same sampling site and submitted to the same salinity gradient (0 to 42g/L) were compared. The results obtained demonstrated that V. corrugata is the most sensitive species to salinity changes and V. decussata is the species that can tolerate a wider range of salinities. Furthermore, our work showed that clams under salinity associated stress can alter their biochemical mechanisms, such as increasing their antioxidant defenses, to cope with the higher oxidative stress resulting from hypo and hypersaline conditions. Among the physiological and biochemical parameters analyzed (glycogen and protein content; lipid peroxidation levels, antioxidant enzymes activity; total, reduced and oxidized glutathione) Catalase (CAT) and especially superoxide dismutase (SOD) showed to be useful biomarkers to assess salinity impacts in clams.